The desirability of an automatic centrifugal force responsive balancing means for the wheels of automotive vehicles, aircraft and the like has been recognized for many years, and quite a large number of United States patents and foreign patents have been granted on devices for this purpose. Three examples of the patented prior art relating to automatic vehicle wheel balancing are U.S. Pat. Nos. 3,006,690; 3,063,754 and 3,314,726.
In spite of the recognition of the problem over a considerable period of time and numerous efforts to provide a means offering a satisfactory solution to the problem, up to the present time, no automatic wheel balancing device has been widely accepted by the public or by industry for balancing vehicular wheels by centrifugal force activated means permanently attached to the wheel structure. The apparent reasons for this lack of acceptance are the undue cost and complexities of prior art devices, their lack of efficiency and reliability of operation, and their inability to "hold" or maintain substantially permanently a balanced wheel condition achieved during high speed rotation of the wheel. The present invention in particular has for one of its main objectives the provision of a permanently installed wheel balancer which will automatically balance the wheel under influence of centrifugal force during rotation, and will hold or maintain the balanced wheel condition almost perfectly when the wheel returns to rest following high speed rotation. If any small amount of imbalance develops in the wheel at rest, this condition will quickly disappear automatically during the next rotational acceleration of the wheel.
Another object of the invention is to provide an automatic and relatively permanent wheel balancing device which is applicable to all sizes of automobile, bus, truck and aircraft wheels, whether of the single or dual types. The essence of the invention resides in the utilization of an annular circular cross section tube body mountable in a fixed position on the wheel rim, preferably at the interior side of the wheel. Within the bore of the annular tube body are placed a plurality of even length uniform diameter preferably plastic tube segments which fill up a major portion of the interior volume of the annular tube body and are free to circulate circumferentially through the bore of the tube body during rotation of the wheel. A dry type lubricant is preferably included in the bore of the annular tube body to reduce to a minimum friction between the relatively movable parts of the device. The remaining interior volume of the annular tube body is filled with lead or steel balls of the proper uniform size and density, the particular material for the balls depending upon whether automotive or aircraft type wheels are involved. The balls are free to circulate within and through the bores of the segmental non-metallic tubing sections and through the main bore of the annular tube body which is preferably formed of a heat treated aluminum alloy.
The precise dimensional relationships between the circulating balls, precut non-metallic tube sections, and the main annular tube body will vary in accordance with wheel size. However, the total weight of the required lead or steel balls and the length of the plastic (preferably nylon) tubing required for each wheel size is directly mathematically proportional to wheel size up and down the scale of sizes, within three main categories of annular aluminum tube body size or outside diameter, namely, 3/8 inch o.d., 1/2 inch o.d., and 3/4 inch o.d. In any case, the sizes and relative weights of components may be calculated empirically for the various applications of the invention, and the details of these calculations, as well as dimensional variations of the parts over the entire range of wheel sizes, are not essential to a full understanding of the invention, and therefore are not included herein. In this connection, the dimensional and mass characteristics of the operational components of the device while important are not so critical that slight variations in the sizes and numbers of the internal moving parts cannot be tolerated in a practical manufactured embodiment of the invention. That is to say, the device will still be entirely satisfactory in operation when such manufacturing variations are involved.
Other features and advantages of the invention will become apparent during the course of the following detailed description.